DKIM-Verify is a software application that can provide DKIM verification for non-DKIM-aware MDAs. Using DKIM-Verify, which functions as a "wrapper" for the MDA, mail originating from and destined for the local domain can be verified. In addition, DKIM-Verify can integrate with mailing list software to provide verification of messages received for later distribution.

SSA Fetchmail is a multi-threaded solution that retrieves new emails from ISP email accounts and forwards them through different channels like email, SMS, or a local SQL repository. It supports IMAP4, POP3, SSL, SMTP TLS delivery, SMPP SMS delivery, and local delivery. SSA Fetchmail supports thousands of email accounts provisioned in a MySQL database. Its performance is better than other solutions.

Scalix Virtual Appliance includes a full installation of the popular email collaboration software Scalix. The only two applications installed in addition to Scalix and its required components are Joe (a simple text editor) and VMware Tools. This appliance should work with any recent version of VMware.

Open-Xchange Virtual Appliance is a virtual appliance/machine that includes a full installation of the popular email collaboration software Open-Xchange. In addition to Open-Xchange, it includes Dovecot, since Open-Xchange is not bundled with any IMAP or POP3 server. It also includes Joe (a simple text editor) and VMware Tools. The appliance was installed using Open-Xchange official guidelines.

Zarafa is an alternative to Microsoft Exchange. It offers the same look and feel of Outlook Web Access (OWA), and fully integrates with Outlook through MAPI. Zarafa Virtual Appliance is a fully working virtual appliance for Zarafa Groupware.

machiNET autoresponder provides vacation messages for Postfix mail servers. It works as a content filter and extracts relevant data (sender and receiver) from the SMTP protocol handshake. It is intended to be used with openLDAP. ispENV2.schema is used for vacation attributes.

Masqmail is an MTA (mail transport agent) for notebooks, workstations, home servers, and generally any host with no permanent network connection. It has special support for multiple transfer routes (e.g. to different mail providers). Address rewriting can be done in several ways. It is a slim replacement for full-blown MTAs such as sendmail, exim, qmail, or postfix and for the intended uses, configuration is much simpler.

OpenSMTPD is an RFC compliant, secure, and simple SMTP server ported from OpenBSD to Linux. It supports the SMTP protocol, including SSL versions for added security, virtual domains, forward files, and external delivery agents like procmail, and can do most of the basic things that other MTA implementations do.

Clement is an email server application. Its main function is to block unwanted mail (spam) as soon as possible in the email exchange process. It accepts or rejects email while the SMTP session, initiated by the email sender, is still pending, accepting legitimate email messages without the need to return an error status to non-existent or "borrowed" return address later. Clement can operate in two modes, either as a standard MTA (as sendmail, Postfix, Exim, Exchange, etc.) to store email in the recipient's own area, or to transmit the mail to an another SMTP server acting as smart spam filtering device. Each email domain name Clement knows about can be treated in one of these two modes depending on the group to which the domain name has been set. Each message is verified by a virus scanner (ClamAV) while the SMTP connection is still open, but the refusal of mail and the reason for refusal is notified to the actual sender. Mail management is done via a Web interface and can be delegated to three administrative levels (Root-Admin, Group-Admin, Domain-Admin). Standard users can access their own logs (sent email status, email rejected, quarantined email, etc.). With this interface, the user can handle the rejection and acceptance of mail. Users who are level "Admin" can access the session logs (via the Web interface). Clement uses a SQL database (PostgreSQL, MySQL) to store and manage logs, user profiles, and dynamic management of directives concerning the sender-receiver relationship.